Today's geophysicists work ever more closely with reservoir engineers and geologists due to the advent of geophysical techniques for reservoir surveillance. Geophysicists have transcended their traditional task of exploration in order to monitor reservoir performance. They are thus called upon to understand the nature of fluid flow within a reservoir and the relationship between reservoir/fluid properties and geophysical observations. It would seem that the physics of fluid flow within a reservoir is, for the most part, unrelated to the phenomena traditionally studied by exploration geophysicists, such as wave propagation within the earth. However, while the physics of fluid flow and...